1. Field of the Invention
The present invention relates to an image forming apparatus and an emission control method.
2. Description of the Related Art
Electrophotographic image forming apparatuses, such as laser printers or digital copiers, sometimes use, as an exposure head (optical writing head), an organic electroluminescence (EL) head in which multiple organic EL devices are arranged in a main scanning direction. The consumption current of organic EL devices is lower compared to light emitting diodes (LEDs), or the like, so that the amount of heat generated by an image forming apparatus can be reduced; therefore, size reduction and simplification of the image forming apparatus are achieved.
However, the emission responsiveness of organic EL devices is poor. Therefore, it is common that a pre-charge is performed to apply an instantaneous high voltage (may be a current) to organic EL devices at the start of an emission, thereby improving the emission responsiveness of the organic EL devices; however, in this case, the pre-charge periods of a large number of organic EL devices are overlapped with one another, which results in an increase in the maximum instantaneous current consumption. Specifically, if a plurality of exposure heads is used, the maximum instantaneous current consumption is further increased.
Here, for example, Japanese Patent Application Laid-open No. 2013-109295 discloses a technology for controlling the emission of multiple light emitting diode array (LEDA) heads by lighting down at least any of the LEDA heads to reduce the maximum current consumption when a photoconductor drum is neutralized.
However, the above-described conventional technology does not reduce the maximum current consumption due to a pre-charge.
In view of the above-described problem, there is a need to provide an image forming apparatus and an emission control method that make it possible to reduce the maximum current consumption due to a pre-charge.